Flashcards in Computer Science Deck (31):
Plaintext is what a computer scientist would use to describe the input message
The number of command line arguments, how many words did you type at the prompt
An array, a contigious block of memory, inside of which are all the things you typed in the prompt.
Define Recursive Calls
A function to call itself, to use it’s own definition again and again, which is bad instinctively unless it keeps getting done on smaller and smaller problems
What are the five layers of memory?
Stack & Heap
What is Val Grind?
A bug spotter for memory mistakes
What does a binary search tree look like?
Every node in this tree is going to have 0,1 or 2 children.
What is a segmentation fault?
A memory related problem in your programme.
The art of making things smaller, ideally without losing information.
What is an IP address?
This gives you the ability to talk to other people and receive messages to other people because you have an address where they can contact you
Define a DNS
Domain Name System, converts IP addresses to pretty nice domains like google.com
Cables that power the internet...
- There are now over three hundred undersea cables stretching 555,000 miles
- That’s enough to circle the earth 22 times
- The longest cable hits thirty nine landing points from Germany to Korea spanning 24,000 miles
- The cables are less than 3 inches thick (opter fibre)
- They transmit 99% of the world’s data
This language is used within the client/the browser
It is executed client side, it is not executed on the server side (unless it’s Node JS)
e.g. Facebook messenger can be open all day, a new row appears without the page having to refresh
You basically have a while loop constantly waiting saying “Did the server send me more data?…. Did the server send me more data? etc.”
IF SO, go ahead with an IF condition and write more text to Messenger, or G-Mail etc.
What are callbacks?
These are just functions which have been configured to be called back at a certain point of time when something happens.
Query from a browser to a server to get more data even after the original browser has been loaded.
What is Bootstrap?
Helps make HTML and CSS look prettier
What is more important than the syntax?
The goal is not to be able to rehearse all the syntax… it’s to understand the fundamental concepts.
He also talks about the power of googling around and using other people’s code.
What is Local Storage?
Store the data inside the browser - this means that you don’t have to remember states on the server side
What is J Query?
Super popular library. It means you don't have to start writing specific code for Chrome, Safari, Firefox etc.
Hack to analyse web pages?
Right click and use developer tools.
What percentage of internet bandwidth does Netflix account for?
What are the three networks?
- LAN - Local Area Network - All computers are in close distance to each other (e.g. In a house, school)
Really good for sharing for printers for example.
Usually connected by cables or wires.
- MAN - Metropolitan Area Network
Bigger than LAN
Often span large cities or a county
Use - Two hospitals on the different side of the city, might want to interconnect computers and share information.
- WAN - Wide Area Network
Across the USA
It needs to span larger than 30 miles. (Anything less is a MAN)
The most famous WAN is the internet.
They use satellite, fibre optic cable, old school copper cable etc in the slower areas
What is the part of your computer that enables you to connect to the internet?
NIC - Network Interface Card
Made up of two halves, one that connects to your computer and the other that connects to a communications media (e.g. ethernet plug
What is a protocol?
Protocols of guy chatting to a girl
One rule is that one person talks at a time
Second rule is that whenever the guy sends a message, it’s expected that she responds
Third protocol is it’s expected she responds accordingly
(E.g. if he says hello, you don’t want her to say bacon. You want her to say the correct thing)
Protocols are the expected norms of communication.
Instead of a guy talking to a girl. We now have a MAC talking to a web server.
Mac will ask “Can I connect to you?”
If it’s a web server, it will say Yes (unless specified otherwise)
The Mac will then respond with GET files google.co.uk/html
What is the ENIAC
Completed in 1946. World's first general purpose electronic programmable computer. It could perform 1000 ten digit additions and subtractions per second.
It was operational for ten years, and it is estimated to have done more arithmetic than the entire human race up to that point.
How big are computer transistors?
Computers use transistors that are smaller than 50 nanometers in size - for reference, a sheet of paper is roughly 100,000 nanometers thick.
They can switch states a million times per seconds and run for decades.
How to represent numbers and letters with binary?
Each binary number is called a bit. It is also done on a scale or 1,2,4,8,16 etc.
If the number was 7, it would have 1 in the 1 collum, 1 in the 2 collum, and 1 in the 4 collum
The largest number a 64 bit can represent is 9.4 quintrillion
Unicode is now the universal one, for emoji's to chineese. It solved the languge problem.
What is an ALU?
Arithmetic and Logic Unit. The mathematical brain of a computer. It is the key to computers.
What causes an overflow?
In general, an overflow occurs when the result of an addition is too large to be represented by the number of bits you are using. This can usually cause an error and unexpected behaviour.
Pacman overflow. After level 256 it would crash and make it impossible to complete as it was 8 bit based.
What is the CPU?
The Central Processing Unit - its job is to execute programmes (e.g. Word, Chrome etc) - these programmes are made up of individual operations called INSTRUCTIONS - these instruct the computer what to do.
The CPU will talk to the memory to read or write articles.